Cognitive Health in Late Life

Cognitive decline, especially memory deficits associated with aging, is a concern of many Baby Boomers in regard to their parents as well as for themselves. Is it true that as we age, despite level of physical fitness and general health, we can expect memory and other cognition changes to occur? Scientific consensus is that many older adults experience decline in their cognitive abilities, and Alzheimer disease accounts for some portion of this decline (Nolan & Blass, 1992; Wilson, Bennett, & Swartzendruber, 1997). Population estimates are that 25 to 50% of adults over age 85 suffer from dementia (Bachman et al., 1992; Evans et al., 1989). Both cross-sectional and longitudinal studies document cognitive decline with age, with level of formal education found to be a modifying factor (Snowdon, Otswald, Kane, & Keenan, 1989). The areas of cognition most likely to show age-related decrements are declarative or episodic memory (i.e., the ability to learn and retain new information) and mental processing skills such as perceptual speed. This refers to the speed with which simple perceptual comparisons can be completed, usually measured with timed tasks that require substituting symbols or making same/different judgments about pairs of visual stimuli (Wilson et al., 1997).

Recent research findings are promising in regard to the possibility of modifying or forestalling the cognitive declines that typically occur with increasing age and preventing the risk of Alzheimer disease. There is a growing body of research that supports the notion of neural plasticity across the lifespan, suggesting that cognitive and physical stimulation helps to maintain perceptual and memory skills. For example, in the Religious Orders Study of 801 older Catholic nuns, priests, and brothers followed for 4.5 years, frequent participation in common cognitive activities was associated with reducing the risk of Alzheimer disease (Wilson et al., 2002). The activities involved information processing as a central feature, not merely engaging in physical exercise. Activities included reading newspapers, magazines, and books; playing games such as cards, checkers, crosswords, or other puzzles; viewing television and listening to radio; and going to museums. On average, a person who was at the 90^th percentile for frequent cognitive activity at baseline was 47% less likely to develop Alzheimer disease compared to a person who engaged in infrequent activity (10^th percentile).

A study examined leisure activities conducted in young and middle adulthood by two groups, 193 patients in their 70s diagnosed with probable or possible Alzheimer disease compared to those reported by 358 healthy older adults (Friedland et al., 2001). The researchers found that the control group had been more active during midlife than the group of cognitively impaired patients for intellectual, passive, and physical activities, after controlling for age, gender, income, and education. Friedland et al. concluded that the diversity as well as the intensity of the intellectual activities conducted in young to middle adulthood was reduced in the patients who later developed dementia.

Results from a study of language decline across the life span, one aspect of the Nun Study, a longitudinal and epidemiological study of aging that investigates risk factors for dementia, also suggest that leisure activities can moderate cognitive impairment in old age (Kemper, Greiner, Marquis, Prenovost, & Mitzner, 2001). The researchers compared grammatical complexity and idea density from autobiographies written by nuns in young adulthood from two groups of the same religious order who lived in different convent locations, Baltimore and Milwaukee. A decline in idea density found for study participants who met criteria for dementia in late life was steepest for the nuns from the Baltimore convent who had higher initial scores. After analyzing differences in convent life between the two groups, the researchers posited that the Milwaukee convent emphasized intellectual activities such as scholarly writing, reading, and biblical study that served to maintain linguistic abilities in old age.

Both intellectual pursuits and physical exercise appear to have a moderating impact on cognitive ability in late life. A recent meta-analytic study of eighteen intervention studies published between 1966 and 2001 examined whether aerobic training enhanced the cognitive functioning of healthy but sedentary older adults (Colcombe & Kramer, 2003). Fitness training was found to have selective benefits for cognitive skills, with the largest benefit occurring for executive-control processes. The degree of the effects of fitness on cognition was moderated by a number of methodological factors including the length and type of the interventions, as well as the gender of the participants, with women benefiting more than men.

What about reversing age-related decline? There is less research to date on this topic, but a very promising research initiative, known as ACTIVE (Advanced Cognitive Training for Independent and Vital Elderly) revealed some promising findings (Ball et al., 2002). A volunteer sample of 2,832 people aged 65 to 94 was studied to assess whether three cognitive training interventions could improve mental skills and daily functioning in adults who lived independently, did not have functional decline, and were not diagnosed with dementia. Each intervention consisted of ten sessions of small group training in one of three skills: memory, inductive reasoning, or processing speed. The results demonstrated that the interventions improved the performance on the measures of the specific cognitive ability for which the participants received training that continued for 2 years, but did not generalize to improvements in everyday functioning. The researchers believe that a longer than 2 year follow up is necessary to assess whether long-term functional gain is possible, given that the subjects showed minimal functional decline at the time of the study.

Regular participation in intellectually stimulating activities and aerobic exercise throughout the lifespan appear to be modifying factors in forestalling and possibly reversing cognitive decline. This burgeoning body of literature provides a strongly hopeful message to the Baby Boomer cohort because routine participation in such activities is clearly within reach of the average American.

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